Afferent projections to the oral motor nuclei in the rat

Abstract

Projections to the trigeminal, facial, ambiguus, and hypoglossal motor nuclei were determined by using horseradish peroxidase histochemistry. Most of the afferent projections to these motor nuclei were from the brainstem reticular formation, frequently in areas adjacent to other synergetic motor nuclei. The reticular formation lateral to the hypoglossal nucleus and reticular structures surrounding the trigeminal motor nucleus projected to each of these other brainstem motor nuclei involved in oral-facial function. Afferent projections to these motor nuclei also were organized along the rostrocaudal axis. Within the reticular formation most of the afferent projections to the trigeminal motor nucleus originated rostral to the majority of neurons projecting to the hypoglossal and ambiguus nuclei, which in turn were rostral to the primary source of reticular afferents to the facial nucleus. In comparison, projections from the sensory trigeminal nuclei and nucleus of the solitary tract were sparse. The interneuron pools that project to the orofacial motoneurons provide one further link in understanding the brainstem substrates for integrating oral and ingestive behaviors.

Characterization of some morphological parameters of orbicularis oculi motor neurons in the monkey

“…For example, brainstem innervation arises from the red nucleus, mesencephalic tegmentum, olivary pretectal nucleus, dorsolateral pontine tegmentum, principle trigeminal nucleus, ventrolateral pontine tegmentum and medullary tegmentum (Travers and Norgren, 1983;Holstege et al, 1984;Holstege et al, 1986;Isokawa-Akesson and Komisaruk, 1987). Additional studies have shown that several regions of the cerebral cortex directly innervate the intermediate subnucleus, including the face region of the primary motor cortex, lateral premotor cortex, supplementary motor cortex, rostral cingulate motor cortex and caudal cingulate motor cortex (Kuypers, 1958;Jenny and Saper, 1987;Morecraft et al, 2001;Gong et al, 2005).…”

Conexões e caracterização neuroquímica de vias neurais envolvidas com o controle dos movimentos mandibulares

“…Although we have used a relative small number of animals, in all cases, the pattern of retrograde-labeled neuron distribution was similar. In concordance with previous results [32], we observed retrograde-labeled neurons in a variety of brainstem areas such as the mesencephalic trigeminal nucleus (Me5), the principal trigeminal nucleus (Pr5), the spinal trigeminal oral and interpolar subnuclei (Sp5O and Sp5I), the supratrigeminal nucleus (Su5), the contralateral Mo5, the juxtatrigeminal and intertrigeminal nuclei, the nucleus reticular pontine caudal (nPC), the gigantocellular nucleus (GI) and GI pars ␣ (GI␣), the parvicellular reticular formation pars ␣ (PCRt␣), the raphe pallidus and obscurus nuclei (RPa and ROb), and the nucleus of the solitary tract (NTS). In addition, we found moderate numbers of retrograde-labeled neurons in the central nucleus of the amygdala (CeA), and in the parasubthalamic nucleus (PSTh) ( Table 1 and Fig.…”

“…These neurons project to the Mo5, as observed by others [20] and confirmed in the present study. Moreover, according to other studies [13,20,32], except in the caudal spinal trigeminal nucleus, retrograde-labeled neurons have been found throughout the trigeminal complex nuclei. The trigeminal sensory nuclei (Me5 and Pr5) may integrate sensory information used for maintenance of masticatory rhythm, which is generated in the reticular formation [25,33].…”

“…The Mo5 is localized in the lateral pontine reticular formation surrounded by a ring of premotor neurons [20]. Employing injection of neuronal tracers, authors have described the distribution of premotor neurons innervating the Mo5 in a variety of brainstem nuclei [20,32]. In addition, studies have shown that electrical stimulation of the amygdala and the area close to the internal capsule induces jaw movement [19].…”

“…Also, in rats, administration of dopamine receptors agonist and antagonist produce jaw movement [22]. Thus, it seems clear that variations in The major sources of dopamine in the central nervous system are the neurons located in the substantia nigra pars compacta, and in the ventral tegmental area [5], but the neural pathways connecting them to the Mo5 have not been observed [32]. Therefore, using tracing techniques and dual label immunohistochemistry we attempted to investigate the anatomical substrate underlying dopaminergic action in jaw motor control.…”